Group items tagged

A new quasicrystal formation has been discovered using computer simulations. The formation consists of hard triangular bipyramids, each composed of two regular tetrahedra sharing a single face, and is described in a paper in Physical Review Letters by Sharon Glotzer and colleagues at the University of Michigan in the US. Great for Luis coming paper .....

The famous Mars Rover Simulator was a piece of the Evolution in Robotic Island Ariadna!!!!! But again, its only an algorithm :) whats new?

Go Plymouth!

from the abstract: "Using a novel imaging and analysis technique on experimental data we estimated pheromone concentrations at all spatial positions in the experimental arena and at different times. Then we derived the response function of individual ants to pheromone concentrations by looking at correlations between concentrations and changes in speed or direction of the ants." [...] "agent based simulations based on the Weber's Law response function determined experimentally produced results compatible with those reported in the literature and reproduced the formation of trails."

Nice article!

why am I not surprised .....

http://www.academia.edu/4210419/Can_climate_models_explain_the_recent_stagnation_in_global_warming A view of well-respected scientists on how to proceed from here, that was rejected from Nature. In any case, a long way to go...

unfortunately it's too early to cheer and burn more coal ... there is also a nice podcast associated to this paper from nature Recent global-warming hiatus tied to equatorial Pacific surface cooling Yu Kosaka & Shang-Ping Xie Nature 501, 403-407 (19 September 2013) doi:10.1038/nature12534 Received 18 June 2013 Accepted 08 August 2013 Published online 28 August 2013 Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century1, 2, challenging the prevailing view that anthropogenic forcing causes climate warming. Various mechanisms have been proposed for this hiatus in global warming3, 4, 5, 6, but their relative importance has not been quantified, hampering observational estimates of climate sensitivity. Here we show that accounting for recent cooling in the eastern equatorial Pacific reconciles climate simulations and observations. We present a novel method of uncovering mechanisms for global temperature change by prescribing, in addition to radiative forcing, the observed history of sea surface temperature over the central to eastern tropical Pacific in a climate model. Although the surface temperature prescription is limited to only 8.2% of the global surface, our model reproduces the annual-mean global temperature remarkably well with correlation coefficient r = 0.97 for 1970-2012 (which includes the current hiatus and a period of accelerated global warming). Moreover, our simulation captures major seasonal and regional characteristics of the hiatus, including the intensified Walker circulation, the winter cooling in northwestern North America and the prolonged drought in the southern USA. Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas

What is the best (wisest) size for a group of individuals? Couzin and Kao put together a series of mathematical models that included correlation and several cues. In one model, for example, a group of animals had to choose between two options-think of two places to find food. But the cues for each choice were not equally reliable, nor were they equally correlated. The scientists found that in these models, a group was more likely to choose the superior option than an individual. Common experience will make us expect that the bigger the group got, the wiser it would become. But they found something very different. Small groups did better than individuals. But bigger groups did not do better than small groups. In fact, they did worse. A group of 5 to 20 individuals made better decisions than an infinitely large crowd. The problem with big groups is this: a faction of the group will follow correlated cues-in other words, the cues that look the same to many individuals. If a correlated cue is misleading, it may cause the whole faction to cast the wrong vote. Couzin and Kao found that this faction can drown out the diversity of information coming from the uncorrelated cue. And this problem only gets worse as the group gets bigger.

Couzin research was the starting point that co-inspired PaGMO from the very beginning. We invited him (and he came) at a formation flying conference for a plenary here in ESTEC. You can see PaGMO as a collective problem solving simulation. In that respect, we learned already that the size of the group and its internal structure (topology) counts and cannot be too large or too random. One of the project the ACT is running (and currently seeking for new ideas/actors) is briefly described here (http://esa.github.io/pygmo/examples/example2.html) and attempts answering the question :"How is collective decision making influenced by the information flow through the group?" by looking at complex simulations of large 'archipelagos'.

what seems to be an impressively detailed space game

> The games we write are always games with a scientific purpose (not training not educational) I'd say investigating how to get the crowd may be an important part of "science of crowdsourcing". So, an obvious example would be comparing how many participants the original ACT space mission game attracted versus a variant implemented in Kerbal and why. Easily made and easily publishable I think. But that's just an obvious example I can give on the spot. I think there is more potential than that, so would not dismiss the idea so definitively. But then, correct me if I'm wrong, social sciences are still not represented in the ACT... Perhaps an idea to revive during the upcoming retreat? ;-)

it's on sale on steam til tomorrow by the way if anyone's interested

I think this is something we/the group can work on for languages? The finding opens the road for simulations I think so can we do something with this? 

Have a nice gaming :-)

Can we do something about this?

they also have this application for Mac and probably also PC : http://www.apple.com/downloads/macosx/games/simulation_and_sports/lunarroversimulator.html

Well, with these huge numerical simulation you're never sure of anything... Anyway the idea sounds quite convincing and simple.

Whops, sorry for the duplicate bookmark above :)

"They found that while the robot can leap to a height of 1.5 metres, such leaps put stresses on the robot's legs that make it more likely to fall over. Leaping to 0.8 metres improved stability but reduced the robot's maximum running speed. Future simulations will determine the precise trade-off between speed and stability."

"Computer simulations of tiny robots with rudimentary nervous systems show that, over hundreds of generations, these virtual machines evolve altruistic behaviors"

I have lost track of all the artificial life/evolutionary computing studies showing the evolution of cooperation/altruism. I don't understand why all the big fuss about this latest one.

Planetary migration poses a serious challenge to theories of planet formation...When multiple planets stir the disk, our simulations yield the new result that large-scale migration ceases. Thus, growing planets do not migrate through planetesimal disks....Although migration through a gaseous disk is an important issue for the formation of gas giants, we conclude that migration has little impact on the formation of terrestrial planets.

Unlike many previous studies of this type, our simulation includes unbound gas, where an appreciable fraction of the baryons in the universe reside.

On the basis of molecular dynamics simulations, we propose a design for a molecular water pump. The design uses a combination of charges positioned adjacent to a nanopore and is inspired by the structure of channels in the cellular membrane that conduct w

Flight simulator in Google Earth.

Artificial life investigates the fundamental properties of living systems through simulating and synthesizing biological entities and processes in artificial media.

Very nice simulation of a heated liquid.